My brief, otherwise forgettable career as a high school football player is dominated by memories of two hits.

The first one occurred in practice. I lined up against a running back who was to run directly at me, without benefit of a blocker. I timed my tackle perfectly, springing upward to hit him in the chest, wrapped my arms around him, picked him up, drove him forward and slammed him to the ground. Without a doubt, his head bounced a time or two as our teammates whooped and the coaches bellowed their approval.

The fathers watching from the sideline admired the hit, too, and word of it reached my father as he arrived to pick me up. "I heard you really 'popped' someone," my father said, unsmilingly. He didn't want me playing football, and he wasn't impressed by the warrior I was attempting to be.

The father-son relationship is at the heart of America's fascination with football, and it's the starting point for filmmaker Sean Pamphilon in The United States of Football. When he became a father, he was as eager as the next American dad for his son to play football. In a chilling home video, we see Pamphilon throwing a football to his toddler son and roughhousing with him to "toughen him up." He flips his son a bit too hard onto the ground, and the camera records his son saying, "Don't crack my skull."

A seasoned sports journalist, Pamphilon couldn't avoid the mounting evidence that football presents long-term health risks for players. The film revisits the appalling demise of Pittsburgh Steelers stalwarts Mike Webster and Justin Strzelczyk, as well as the early onset dementia experienced by such old-timers as John Mackey, a Hall of Fame tight end who later became president of the NFL Players Association, and Ralph Wenzel, a journeyman lineman who later coached at North Carolina Central University.

The NFL's response to initial efforts to link football to dementia and chronic traumatic encephalopathy (CTE) was denial. After NFL Commissioner Roger Goodell was upbraided in a Congressional hearing by Rep. Linda Sánchez, the league changed tack. It paid for studies, it created assistance funds, it encouraged improved helmet design, it educated players about the risks. All of this may be dismissed as public relations—and it's certainly that, too. The NFL's recent $675 million settlement with more than 4,500 retired players was widely seen as a tactical victory for the league—limiting the financial payout while admitting no wrongdoing.

But as journalist Malcolm Gladwell, a fierce critic of the game, points out, the sport is on a collision course with itself. Violence is at the core of football's appeal. As the dangers of the sport become more obvious, the talent will be drawn from a more and more marginal population, much like the Army, which is reserved for "those who have no other options, for whom the risks are acceptable," Gladwell says.

"But it will become a ghettoized sport, not a mainstream American pastime," he says. "You would be stunned by how quickly it can go away."

One doesn't have to look too closely before agreeing with a Pittsburgh radio personality named Mark Madden when he says, "When you break the economic model of football down to its most basic, it's rich white people exploiting poor black people."

Much of the testimony in The United States of Football, which shouldn't be confused with the forthcoming Frontline documentary League of Denial (from which ESPN notoriously dissociated itself), will be familiar to those who have been paying attention to reports of concussions, CTE and the grisly trend of football players committing suicide by shooting themselves in the chest. But some of the most compelling passages are the portraits of the near-vegetative Mackey and Wenzel, and their activist wives.

Elsewhere, the film follows young retirees Sean Morey, a hell-for-leather special teams player-turned-activist, and Kyle Turley, a lineman-turned-country singer, as well as longtime Steelers linebacker James Harrison, an intelligent man saddled with a reputation as a dirty player. Not yet 40, Morey and Turley are already experiencing debilitating symptoms. All three men are as tough as they get, yet they grapple with their feelings about the price they've paid with their health.

Pamphilon is the filmmaker who released the recording of St. Louis Saints defensive coach Gregg Williams urging his players to target opponents for injury. Despite his film's focus on the NFL, he efficiently eviscerates youth football, where the coaches often have no training, no psychological screening and much unresolved desire to live vicariously through their charges.

And what about the second hit I remember from my youthful football career? It occurred in a game, when I was sprinting down the field on the kickoff team. The kick returner went away from me, toward the far sideline. I saw that my teammates were making the tackle so I slowed down. As I did, I noticed an incoming blocker in the right side of my periphery. I was unclear whether I should avoid contact, but I saw him lunge at me, forearms swinging upward—BAM—I was flat on my back, completely clotheslined. I scrambled to my feet and trotted off the field, dizzy and stunned by the perfectly legal violence I had experienced.

My football career didn't last much past that season. I returned to soccer—which, incidentally, also produces injuries at a high rate. While one can argue that soccer requires more skill than football—everyone has to be able to handle the ball competently, for starters—it is also beside the point. Football in America is more than a game. It's a rite of male passage and a theatrical enactment of war. And The United States of Football knows we continue to love it, even as it leaves maimed bodies in its wake.